Inflation after preheating

Abstract

Preheating after inflation may lead to non-thermal phase transitions with symmetry restoration. These phase transitions may occur even if the total energy density of fluctuations produced during reheating is relatively small as compared with the vacuum energy in the state with restored symmetry. As a result, in some inflationary models one encounters a secondary, non-thermal stage of inflation due to symmetry restoration after preheating. We review the theory of non-thermal phase transitions and make a prediction about the expansion factor during the secondary inflationary stage. We then present the results of lattice simulations which verify these predictions, and discuss possible implications of our results for the theory of formation of topological defects during non-thermal phase transitions.